1. Field of the Invention
The invention relates to a device for chlorinating water, and more particularly to an electrolytic cell of the diaphragm type having feeding and withdrawl means, such as for domestic-size applications.
2. Prior Art
The disinfection of the water in small swimming pools is normally accomplished by adding chlorine chemicals, e.g. in the form of chlorine tablets or sodium or calcium hypochlorite, which release or form chlorine in the water. This method is advantageous in that it does not require handling of liquid or gaseous chlorine and in that it does not require complex and expensive apparatus; the dosage and the addition is normally accomplished entirely manually.
However, this method also has several disadvantages. For example, to maintain the chlorine content of the water at a suitable and fairly constant level, it is necessary to add the chemicals relatively frequently and in accurate amounts. Moreover, the commercially available chlorine chemicals are unstable and consequently cannot be stored for long periods without losing some of their chlorinating effect. The added chemicals also cause a gradual increase of the content of foreign substances in the water. In addition, the chlorinating chemicals often have an undesired influence on the pH of the water, and from time to time other chemicals (hydrochloric acid) have to be added to control the pH.
The above-mentioned disadvantages may be avoided if the chlorine is added as gaseous chlorine. Gaseous chlorine may be fed to the water from pressurized steel containers, but because of the hazards involved in the handling of gaseous chlorine, chlorination by means of pure chlorine stored in pressurized containers is feasible only in larger, e.g. municipal, pools or plants. For smaller, residential pools or other installations which are not constantly operated or supervised by skilled attendants such chlorination is not recommendable.
For smaller pools and water supplies one may use gaseous chlorine, provided the chlorine is produced on the spot, e.g. by the electrolysis of a chloride solution, and fed directly into the water. The quantities of gaseous chlorine produced in the chlorinator then are always sufficiently small for simple safety measures to be adequate to practically eliminate the danger of chlorine poisoning.
Electrolytic chlorinators intended for use in residential swimming pools or other smaller installations are known in many different forms; U.S. Pat. No. 3,767,557 shows an example. However, in spite of the advantages that electrolytic chlorinators offer, such chlorinators have not gained widespread adoption, and the initially described method comprising addition of chlorine tablets or sodium or calcium hypochlorite is still prevailing as far as residential swimming pools and other small installations are concerned.